dsp: ensure unassign memory happen when pause voice call failed

When voice call pause failed, cvp cal deregister is not called
to make hyp unassign memory happen.

Fix it by calling cvp cal deregister even if voice call pause
failed.

Change-Id: I88afa951e0be50ca06509e9e51ce484b75dcc7d4
Signed-off-by: Kunlei Zhang <kunleiz@codeaurora.org>